Support for Python 3.12

[mbehrle]

Quoting from https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1061833 :

With python3-defaults from experimental (Python 3.12), the package fails its autopkg 
tests:

[...]
559s autopkgtest [14:04:52]: test run-testsuite3: [-----------------------
560s ============================= test session starts 
==============================
560s platform linux -- Python 3.12.1, pytest-7.4.4, pluggy-1.3.0
560s rootdir: /tmp/autopkgtest.ibor7H/autopkgtest_tmp
560s collected 0 items / 1 error
560s
560s ==================================== ERRORS 
====================================
560s _____________________ ERROR collecting test/test_litmus.py 
_____________________
560s ImportError while importing test module 
'/tmp/autopkgtest.ibor7H/autopkgtest_tmp/test/test_litmus.py'.
560s Hint: make sure your test modules/packages have valid Python names.
560s Traceback:
560s /usr/lib/python3.12/importlib/__init__.py:90: in import_module
560s     return _bootstrap._gcd_import(name[level:], package, level)
560s test/test_litmus.py:15: in <module>
560s     import pywebdav.server.server
560s pywebdav/server/server.py:33: in <module>
560s     from pywebdav.lib.INI_Parse import Configuration
560s pywebdav/lib/INI_Parse.py:3: in <module>
560s     from six.moves.configparser import SafeConfigParser
560s E   ImportError: cannot import name 'SafeConfigParser' from 
'configparser' (/usr/lib/python3.12/configparser.py). Did you mean: 
'RawConfigParser'?
560s =============================== warnings summary 
===============================
560s test/test_litmus.py:91
560s   /tmp/autopkgtest.ibor7H/autopkgtest_tmp/test/test_litmus.py:91: 
SyntaxWarning: invalid escape sequence '\d'
560s     if len(re.findall('^ *\d+\.', line)):
560s
560s test/test_litmus.py:130
560s   /tmp/autopkgtest.ibor7H/autopkgtest_tmp/test/test_litmus.py:130: 
SyntaxWarning: invalid escape sequence '\d'
560s     if len(re.findall('^ *\d+\.', line)):
560s
560s -- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
560s =========================== short test summary info 
============================
560s ERROR test/test_litmus.py
560s !!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection 
!!!!!!!!!!!!!!!!!!!!
560s ========================= 2 warnings, 1 error in 0.10s 
=========================
560s autopkgtest [14:04:53]: test run-testsuite3: -----------------------]
560s autopkgtest [14:04:53]: test run-testsuite3:  - - - - - - - - - - 
results - - - - - - - - - -
560s run-testsuite3       FAIL non-zero exit status 2

[andrewleech]

Thanks for the report & details, I don't have any bandwidth to work on this myself, but certainly open to PR's !